In the steps involving making of the semiconductor devices, cleaning is required at various steps to remove organic/inorganic residues. Cleaning to improve residue removal desired in semiconductor manufacturing processing, include; post-CMP (chemical mechanical planarization) cleaning, photo-resist ash residue removal, photoresist removal, various applications in back-end packaging such as pre-probe wafer cleaning, dicing, grinding etc.
A particular need for improved cleaning exists in post CMP cleaning of copper interconnects. Semiconductor wafers contain copper interconnection, which connects the active devices on the wafer with each other to from a functioning chip. The copper interconnects are formed by first forming trenches in a dielectric. A thin metallic barrier is typically deposited on the dielectric layer to prevent copper diffusion into the dielectric. This is followed by deposition of copper into the trenches. After the copper deposition, the wafer is polished using a process referred to as Chemical Mechanical Planarization (CMP). This process results in removal of excess copper deposits and planarizes the surface for the subsequent photolithographic step. After the CMP step, the wafer surface contains a large number of defects, which if not cleaned from the surface would result in a defective chip as an end-product. Typical defects after a CMP process are inorganic particles, organic residues, chemical residues, reaction products on the surface due to interaction of the wafer surface with the CMP slurry and elevated levels of undesirable metals on the surface. After the polishing step, the wafer is cleaned, most commonly using a brush scrubbing process. During this process, a cleaning chemistry is dispensed on the wafer to clean the wafer. The wafer is also later rinsed with deionized (DI) water, before a drying process is performed.
Patents in the generally in the field of the present application include:
JP 11-181494; U.S. Pat. No. 6,440,856; U.S. Pat. No. 7,497,966 B2; U.S. Pat. No. 7,427,362 B2; U.S. Pat. No. 7,163,644 B2; PCT/US2007/061588; U.S. Pat. No. 7,396,806; U.S. Pat. No. 6,730,644; U.S. Pat. No. 7,084,097; US 2003/0129078; and, US 2005/0067164.
None of the prior art could anticipate the improvement in residue removal ability that the present invention has shown with the use of the specific polymer and bases of the present invention. The formulations in the present invention were found to be very effective in removing the residues left behind by the above described CMP polishing process.